Process for removing sulfur from crude oil

ABSTRACT

A process for removing sulfur from crude oil by contacting with calcium carbonate-containing material at atmospheric pressures and temperatures less than about 100*F.

[451 Nov. 26, 1974 PROCESS FOR REMOVING SULFUR FROM CRUDE OIL [76] Inventor: Robert D. Ellender, Jr., Star Route 2, Box 357, Sulphur, La. 70663 [22] Filed: Dec. 3, 1973 [21] Appl. No.: 421,127

[52] U.S. Cl. 208/226, 208/284 [51] Int. Cl ..C10g19/00 [58] Field of Search 208/226, 283, 284, 230, 208/203 [56] References Cited UNITED STATES PATENTS 240,094 4/1881 Connelly 208/283 1,954,116 4/1934 Caldwell 1, 208/283 2,034,712 3/1936 Dolbear 208/283 2,053,209 9/1936 Snow 208/282 2,321,290 6/1943 Giraitis 208/268 2,322,554 6/1943 Winding... 208/283 2,348,543 5/1944 J0hns0n......,. 208/226 2,361,651 10/1944 Proell et a1. 208/226 2,481,300 9/1949 Engel 208/262 OTHER PUBLICATIONS The Molten Carbonate Process For Sulfur Oxide Emissions 11/1969, Chemical Engineering Progress (Vol. 65, No. 11).

Primary ExaminerDelbert E. Gantz Assistant Examiner-Juanita M. Nelson atmospheric pressures and temperatures less than about 100F.

8 Claims, N0 Drawings BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates broadly to the treating of petroleum crude oil, and more particularly to the removal of sulfur from the crude oil.

2. Prior Art With the increasing emphasis on pollution and the resulting demand for low sulfur content petroleum crude oil, a severe need for economically producing low sulfur crude has arisen in view of the shortage of natural low sulfur crude.

In most oil refineries today the sulfur is generally removed after the crude oil has been fractionated which requires the use of different desulfurization processes, as well as expensive equipment which have high maintenance costs and require extreme operating conditions. Examples of prior art processes can be seen in US. Pat. Nos. 59,177, 1,942,054, 1,954,116, 2,177,343, 2,321,290, 2,322,554, 2,348,543, 2,361,651, 2,481,300, 2,772,211, 3,294,678,

3,402,998 and 3,699,037. However, these processes are not readily adapted to treating crude oil.

SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide a desulfurization process for the treatment of crude oil.

, PREFERRED EMBODIMENTS OF THE INVENTION As indicated in the above mentioned patents, the use of calcium carbonate in desulfurization of fractionated,

products is well known. In each of these processes the calcium carbonate, with or without other desulfurizing agents, is contacted with the fractionated products at either high temperatures or pressure, or both. In these processes the temperatures, pressures and other operating conditions depend upon the type of sulfur compounds found in the fractionated products, the fractionated product being treated, as well as other factors. However, none appear satisfactory unless there is at least either high temperature or pressure. Therefore, it is surprising that a low temperature, low pressure cal.- cium carbonate desulfurization process for treating crude oil could work. Ithas been found that by contacting a calcium-containing material directly with crude oil at basically atmospheric pressure and temperatures below about 100F that the sulfur level of the crude oil can be reduced more than 50 percent and in most cases below 1 percent by weight.

Calcium carbonate-containing material that can be used include but not necessarily are limited to industrial lime, chalk, calcite, dolomite and limestone, and more preferably a high calcium marble limestone that is a ZOO-mesh in powder form. As is seen in the examples below, the marble limestone results in a lower sulfur content and a still lower sulfur content if it is in powder form having an average size of 200-mesh.

EXAMPLE 1 A treating vessel was filled with one (1) quart of West Texas Sour crude oil having a sulfur content of 1.67 weight percent before treatment. The crude oil was maintained at atmospheric pressure and at a temperature of about 82F. Next, two (2) ounces of 200- mesh powdered Batesville marble limestone was uniformly poured over the top of the crude oil and allowed to perculate down through the crude oil. After all the limestone had completely perculated through the crude oil and had settled at the bottom of the treating vessel a sample of the treated crude oil was removed and tested for sulfur content. These steps were repeated at the same temperature and pressure on the same crude oil, except that the calcium carbonate-containing material was changed to a Pelican State lime, a nonpowdered pelleted lime, and then to an industrial lime. The results of these tests are given below in Table 1.

Table l. Effect of Type of CaCO MalerialUsed.

In contacting thecalcium carbonate-containing material with the, crude oil, it is important that as much as possible of the crude oil comes into contact with the material. For this reason, it is preferred that the mixture be agitated by any of various known means such as revolving blades, etc. If no agitation is to be used then it is preferred that the calcium carbonatecontaining material be poured into the crude oil and not vice versa as that could result in caking 0f the calcium carbonate-containing material causing aloss in its sulfur removing efficiency.

It is also preferred that the calcium carbonatecontaining material be contacted with the crude oil in a non-aqueous environment so as not to impair its sulfur removing capabilities as seen in the example results below.

EXAMPLE 2 A treating vessel was filled with 55 gallon drums of Arabian crude oil having an initial sulfur levelof 2.52 weight percent and maintained at atmospheric pressures and at about F. To this crude oil was added l 2 pounds of ZOO-mesh powdered marble limestone which was allowed to perculate through. the crude oil. After all of the limestone had settled the treated crude oil was examined for sulfur content. The above test was then repeated, except that 12 gallons of water was added to the crude oil before the limestone. The treated crude oil was then tested for sulfur content. The results of these tests are found in Table 2 below.

MIXTURE SULFUR CONTENT AFTER TREATMENT Crude Limestone .78

Crude Water Limestone 2.16

Table 2. Effect of H on sulfur level.

EXAMPLE 3 AMOUNT OF LIMESTONE SULFUR CONTENT IN OUNCES AFTER TREATMENT Table 3. Effect of Amount of Limestone on Sulfur Level of Crude Oil.

It is preferred that atmospheric pressure be employed, as this will allow sufficient contact time between the crude oil and the calcium carbonatecontaining material. Although some pressure in the reaction zone is allowable, it should not be so much that the contact time between the crude oil and calcium carbonate-containing material is decreased to any great extent.

The reduction in the sulfur level will improve as the reaction temperature is decreased as is seen by Table 4. It appears that only at temperatures below about 100F is significant sulfur reduction obtained. The lower limit of the temperature range would be that temperature which would not freeze the crude oil or in crease its viscosity to the point that the limestone could not perculate through the crude oil.

EXAMPLE 4 A treating vessel was filled with 1 quart of West Texas Sour crude oil having an initial sulfur content of 2.62 weight percent sulfur. Next, ZOO-mesh. powdered Batesville marble limestone was perculated through one ounce of the crude oil maintained at 82F and at atmospheric pressure. After all of the limestone had perculated through the crude oil, the sulfur level of the treated crude oil was measured. This procedure was repeated, except that the reaction temperature was changed to 200F.

TEMP. TREATED TREATED TREATED CRUDE CRUDE CRUDE "F OIL SULFUR OIL SULFUR OIL SULFUR LEVEL, WTf/r LEVEL, WT.71 LEVEL, T/7r (BATESVILLE) (PELICAN (INDUSTRIAL STATE) LIME) Table 4.

Effect of temperature on sulfur level of treated crude.

Other alternative steps and conditions are, of course, obvious to one skilled in the art and are included within the description of this invention.

Another advantage of the use of the calcium carbonate-containing material under the conditions of this invention is that substantial reduction in the vanadium level of the crude oil is achieved. This can be important in subsequent refining processes such as coking.

EXAMPLE 5 A treating vessel was filled with 1 quart of Arabian crude oil having an initial sulfur content of 2.52 weight percent and an initial vanadium content of 0.008 weight percent. To this crude oil was added 1 ounce of ZOO-mesh powdered marble limestone which was allowed to perculate through the crude oil under atmospheric pressures and temperatures of about 50F. The treated crude oil was then treated for its vanadium content and was found to contain only 0.004 weight percent, a 50 percent reduction from the initial untreated level.

What I claim is:

l. A crude oil desulfurization process which comprises:

a. contacting said crude oil with a calcium carbonatecontaining material at atmospheric pressures and temperatures less than about F. to form a partially desulfurized crude oil product and a residue product; and

b. separating said desulfurized crude oil product from said residue product.

2. A process according to claim 1 wherein said calcium carbonate-containing material is limestone.

3. A process according to claim 2 wherein said limestone is a marble limestone of ZOO-mesh in a powder form.

4. A process according to claim 3 wherein 1-4 ounces of said limestone is used per quart of said crude oil.

5. A process according to claim 1 wherein said calcium carbonate-containing material contacts said crude oil by perculating said material through said crude oil.

6. A process according to claim 5 wherein said mateagitated during contact.

rial is uniformly perculated through said crude oil. 8. A process according to claim 1 wherein said con- 7. A process according to claim 1 wherein said caltacting occurs in a non-aqueous environment.

cium carbonate-containing material and crude oil are 

1. A CRUDE OIL DESULFURIZATION PROCESS WHICH COMPRISES: A. CONTACTING SAID CRUDE OIL WITH A CALCIUM CARBONATECONTAINING MATERIAL AT ATMOSPHERIC PRESSURES AND TEMPERATURES LESS THAN ABOUT 100*F. TO FORM A PARTIALLY DESULFURIZED CRUDE OIL PRODUCT AND A RESIDUE PRODUCT; AND B. SEPARATING SAID DESULFURIZED CRUDE OIL PRODUCT FROM SAID RESIDUE PRODUCT.
 2. A process according to claim 1 wherein said calcium carbonate-containing material is limestone.
 3. A process according to claim 2 wherein said limestone is a marble limestone of 200-mesh in a powder form.
 4. A process according to claim 3 wherein 1-4 ounces of said limestone is used per quart of said crude oil.
 5. A process according to claim 1 wherein said calcium carbonate-containing material contacts said crude oil by perculating said material through said crude oil.
 6. A process according to claim 5 wherein said material is uniformly perculated through said crude oil.
 7. A process according to claim 1 wherein said calcium carbonate-containing material and crude oil are agitated during contact.
 8. A process according to claim 1 wherein said contacting occurs in a non-aqueous environment. 